Radar systems are employed for a variety of uses. As an example, a radar system may be used as a range-measurement system to estimate the position of an object in motion. One example of a range-measurement system is a radar-altimeter system, which may be employed on an aircraft, for instance. A radar-altimeter system may be used to determine the altitude of an aircraft, thereby informing an operator that the aircraft is flying too low or that terrain is rising, relative to the aircraft, to meet the aircraft.
A radar-altimeter system (or radar system, more generally) typically employs one or more transmit antennas and one or more receive antennas. In operation, the radar-altimeter system may transmit a transmit-signal, via a transmit antenna, toward a target such as the ground. The radar altimeter may then receive, via the receive antenna, a received-signal. The received-signal may include a target component that includes a portion of the transmit-signal reflected off of the target and subsequently received by the receive antenna. With knowledge of the propagation speed of the transmit-signal, the system may then determine the altitude of the aircraft by measuring the time between transmitting the transmit-signal and receiving the target component of the received-signal.
The received-signal may also include a leakage component. As an example, the received-signal may include a leakage component when the receive antenna receives a portion of the transmit-signal directly from the transmit antenna. As another example, the received-signal may include a leakage component in a situation in which the transmit-signal bounces off certain non-target objects (e.g., a vehicle appendage such as a fuel tank) and the receive antenna receives a portion of the bounced transmit-signal. When the received-signal includes a leakage component, a radar system may have greater difficulty in accurately tracking targets, especially in radar-altimeter applications in which an aircraft is flying at a relatively low altitude.